@article {11955, title = {In Situ X-Ray Absorption Spectroscopy Study of Hydrogen Absorption by Nickel-Magnesium Thin Films}, journal = {Physical Review B}, volume = {67}, number = {8}, year = {2002}, month = {02/2003}, abstract = {

Structural and electronic properties of co-sputtered Ni-Mg thin films with varying Ni to Mg ratio were studied by in situ x-ray absorption spectroscopy in the Ni L-edge and Mg K-edge regions. Codeposition of the metals led to increased disorder and decreased coordination around Ni and Mg compared to pure metal films. Exposure of the metallic films to hydrogen resulted in formation of hydrides and increased disorder. The presence of hydrogen as a near neighbor around Mg caused a drastic reduction in the intensities of multiple scattering resonances at higher energies. The optical switching behavior and changes in the x-ray spectra varied with Ni to Mg atomic ratio. Pure Mg films with Pd overlayers were converted to MgH2: The H atoms occupy regular sites as in bulk MgH2. Although optical switching was slow in the absence of Ni, the amount of H2 absorption was large. Incorporation of Ni in Mg films led to an increase in the speed of optical switching but decreased maximum transparency. Significant shifts in the Ni L3 and L2 peaks are consistent with strong interaction with hydrogen in the mixed films.

}, doi = {10.1103/PhysRevB.67.085106}, author = {Baker Farangis and Ponnusamy Nachimuthu and Thomas J. Richardson and Jonathan L. Slack and Rupert C.C. Perera and Eric M. Gullikson and Dennis W. Lindle and Michael D. Rubin} } @conference {11966, title = {Influence of stoichiometry on the electrochromic cerium-titanium oxide compounds}, booktitle = {11th International Conference of Solid State Ionics}, year = {1997}, month = {11/1997}, address = {Honolulu, Hawaii}, abstract = {

CeO2-TiO2 finds use as passive counter-electrode in electrochromic devices. Thin films were produced by dc-sputtering in a wide range of compositions. Influence of total pressure and oxygen partial pressure on the optical constants of TiO2 was investigated. Slightly substoichiometric TiO2 films exhibit a red-shift of the bandgap. The TiO2 content in the compound essentially determines the degree of cathodical coloring upon Li+ intercalation. However, pure TiO2 films with comparable visible transmittance in the clear state behave differently during electrochemical cycling depending on oxygen stoichiometry. Films that are deposited at higher total pressure are more oxygen rich and require initial formatting until current voltage cycles become stable. CeO2-TiO2 films of intermediate compositions have the relatively highest charge capacity. Comparison with atomic force microscopy indicates a correlation of small grain size with high charge capacity.

}, keywords = {band gap, charge capacity, electrochromic cerium titanium oxide, grain size, optical constants, rms roughness, tio2}, author = {Klaus von Rottkay and Thomas J. Richardson and Michael D. Rubin and Jonathan L. Slack and Lisen Kullman} }